Screw propeller



FIG. 1 is a perspective view of screw propeller according to the new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a right view thereof;

FIG. 5 is a left view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the drawings depict portions of the screw propeller that form no part of the claimed design. 

CLAIM The ornamental design for screw propeller, as shown and described. 